Photographic lighting system and method

ABSTRACT

Photographic lighting devices and systems having multiple electrical energy storage/discharge (EESD) elements and/or multiple light sources in a single photographic lighting device to perform one or more photographic lighting effects. In one exemplary aspect, independent control of one or more light sources connected to a first EESD bank and another one or more light sources connected to a second EESD bank, such as via control circuitry, may be utilized in producing various lighting effects.

RELATED APPLICATION DATA

This application claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 61/899,870, filed Nov. 4, 2013, and titled “Photographic Lighting System and Method,” which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of photographic lighting. In particular, the present invention is directed to a photographic strobe system and method.

BACKGROUND

Proper lighting is an essential element for creating desirable photographs. While many photographs are made using only natural or other ambient lighting, many more are made using dedicated photographic lighting provided solely for the purpose of capturing photographic images having the “right” exposure desired by the photographer. Common photographic lighting devices are strobes and other flashes.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, the drawings show aspects of one or more embodiments of the invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 is a high-level block/schematic diagram of an example of a photographic strobe system;

FIG. 2A is graph of exemplary flash intensity-versus-time curves for a TTL pre-flash, a full-power, first-curtain image-capture flash and a reduced-power, first curtain image-capture flash;

FIG. 2B is a graph of exemplary flash intensity-versus-time curves for a full-power, second-curtain image-capture flash and a reduced-power, second curtain image-capture flash;

FIG. 2C is a graph of an exemplary flash intensity-versus-time curve for a constant-level image-capture flash;

FIG. 2D is a graph of exemplary flash intensity-versus-time curves for multiple flashes strobed within a single exposure period;

FIG. 2E is a graph of exemplary flash intensity-versus-time curves for multiple rapidly fired flashes for rapidly capturing sequential images;

FIG. 3A is a graph of exemplary flash intensity-versus-time curves illustrating enhanced intensity image capture flashes that can be achieved with a photographic strobe system of the present disclosure;

FIG. 3B is a graph of exemplary flash intensity-versus-time curves for a combined first- and second-curtain sync image-capture flash that can be achieved with a photographic strobe system of the present disclosure;

FIG. 3C is a graph of exemplary flash intensity-versus time curves for a combined first-curtain sync plus constant-level image capture flash that can be achieved with a photographic strobe system of the present disclosure;

FIG. 3D is a graph of exemplary flash intensity-versus time curves for a combined second-curtain sync plus constant-level image capture flash that can be achieved with a photographic strobe system of the present disclosure;

FIG. 3E is a graph of exemplary flash intensity-versus-time curves for multiple flashes strobed within a single exposure period that can be achieved with a photographic strobe system of the present disclosure;

FIG. 3F is a graph of exemplary flash intensity-versus-time curves for multiple rapidly fired flashes for rapidly capturing sequential images that can be achieved with a photographic strobe system of the present disclosure;

FIG. 5 is a schematic diagram of an exemplary strobe light having two light sources;

FIG. 7 is an isometric view of an exemplary photographic strobe device;

FIG. 8 is a rear elevational view of the photographic strobe device of FIG. 5;

FIG. 9 is a diagrammatic view of an exemplary photographic system;

FIG. 10 is a diagrammatic view of another exemplary photographic system; and

FIG. 11 is a one example of an image acquisition in a camera that has two moving shutters;

DETAILED DESCRIPTION

The present disclosure includes description of implementations of a photographic lighting device system and method involving multiple electrical energy storage/discharge (EESD) elements and/or multiple light sources in a single photographic lighting device to perform one or more photographic lighting effects.

A photographic lighting device is a device that provides light that can be used during photographic image acquisition. Examples of a photographic lighting device include, but are not limited to, a flash device, a constant light source, a near constant light source, and any combinations thereof. Examples of a flash device include, but are not limited to, a strobe device (e.g., a studio strobe light), a photographic speedlight, and any combinations thereof. Several examples below that are described with respect to FIGS. 1 to 10 utilize the term “strobe” and “strobe device” for convenience. It is contemplated and should be understood that where these terms are used herein, any photographic lighting device could also be used in place of the “strobe.” For example, a photographic speedlight can replace the studio strobe and have the features and structures described below.

A photographic image acquisition typically involves the use of a camera having a sensor for capturing an image. Example sensors include, but are not limited to, an electronic sensor, a film sensor, and any combinations thereof. Many modern cameras (e.g., a digital SLR camera) utilize electronic sensors. An image acquisition window is a timeframe in which an image is acquired (e.g., using a photographic sensor). The beginning and end of an image acquisition window may be controlled in various ways known in the photographic arts. In one example, a camera may include one or more shutters for blocking and/or allowing light to pass to a sensor. In another example, electronic gating of a sensor can be utilized to start and stop an image acquisition window (e.g., gating the data acquisition from an electronic sensor in a shutter-less camera). FIG. 11 illustrates one example of an image acquisition in a camera that has two moving shutters (a first shutter and a second shutter). In a starting position, the shutter mechanism is closed and blocks light to a sensor of the camera. The first shutter blade moves to open and expose the sensor to the light of the image (e.g., light passing through an aperture of a lens). The second shutter blade moves to close and block light from passing to the sensor. At slower shutter speeds (i.e., longer exposures), the first shutter may stop movement and be fully open before the second shutter starts to move to block the sensor. At faster shutter speeds (i.e., shorter exposures), the second shutter blade may start to block the sensor prior to the first shutter blade completing its movement across the sensor. In FIG. 11, a plot 1105 shows the position of a first shutter blade over time. The initial flat portion of the plot indicates a position that blocks light to a sensor. The later flat portion of the plot indicates a position in which the first shutter is no longer moving and no longer blocks light to the sensor. The sloped portion of the plot indicates the movement of the first shutter blade across the sensor from the position that blocks light to the position that allows light to pass. During the sloped portion the shutter blade partially blocks the sensor. Plot 1110 shows the position of a second shutter blade over time. The initial flat portion of the plot indicates a position of the second shutter blade that allows light to pass to the sensor. The later flat portion of the plot indicates a position of the second shutter blade that in which the shutter blade blocks light to the sensor. The sloped portion of the plot indicates the movement of the second shutter blade across the sensor from the position that allows light to pass to the position that blocks light. During the sloped portion the second shutter blade partially blocks light to the sensor.

Time segment 1115 (between dotted lines 1120 and 1125) indicates a segment of time in which neither shutter blade is blocking light to the sensor. This time segment can be viewed as an image acquisition window. In another example, an image acquisition window starts at the beginning of first shutter blade movement and ends at the end of second shutter blade movement. In yet another example, an image acquisition window starts when the first shutter blade moves to a position that starts to allow light to pass to a sensor (this position may be some time after the blade starts to move due to space on the side of a sensor over which a blade may move) and ends when a second shutter blade moves to a position that fully blocks light from passing to the sensor (this position may be some time before the blade stops movement). In still another example, an image acquisition window may be gated electronically with or without shutter movements. A shutter speed of an image acquisition is typically the time between the first shutter blade starting to move and the second shutter blade starting to move (this can also be measured from the time when the first shutter blade stops movement to the second shutter blade stopping movement). As discussed above, at faster shutter speeds (e.g., greater than 1/250^(th) of a second) the movement of the shutter blades may overlap providing for no fully open image acquisition window. In such an example, an open slit between the shutter blade edges allows light to pass to different portions of the sensor as the slit moves across the sensor.

FIG. 11 shows a plot of light emission intensity 1130 for a photographic lighting device that is caused to emit light in association with the image acquisition window for the camera. A flash pulse of light 1135 is emitted in time segment 1115 such that the light emission is available to the sensor during the fully open image acquisition window. In one example, at faster shutter speeds an image acquisition window can be measured from the time when the first shutter blade moves to a position that starts to allow light to pass to a sensor and ends when a second shutter blade moves to a position that fully blocks light from passing to the sensor.

It is noted that the plotting of a first and second shutter blade movement can be combined into a single plot that looks a bit like a parallelogram. This type of plot is used below with respect to FIGS. 3A to 3E and 4A to 4F to show exposure periods associated with various light emissions.

In some examples of TTL (“through the lens”) flash photography, a preflash is utilized to provide light to a scene that is measured through the lens of the camera. A preflash typically occurs prior to image acquisition (e.g., prior to a first shutter blade beginning movement). The measurement of the light is utilized to determine a power level for a main flash that will be used during image acquisition. Prior art systems known to the inventor utilize a single flash light source for both the preflash and the main flash. For example, a photographic speedlight includes a single flash tube for emitting light for both the preflash and the main flash.

A photographic lighting device may include two or more EESD elements for providing flexibility to the type of light emission during an image acquisition window, the number of light emissions during an image acquisition window, and/or the position of one or more light emissions during an image acquisition window. Such a photographic lighting device may provide a variety of light emission functionalities. Example functionalities that may be provided by a multiple EESD element single photographic lighting device include, but are not limited to, using a first light source coupled to one or more EESD elements as a TTL preflash and a second light source of the same lighting device for a main TTL flash; using multiple EESD elements fired together (e.g., coupled to multiple light sources, coupled to a single light source) to emit light for a single image acquisition; using multiple EESD elements fired in series (e.g., coupled to a single light source, coupled to multiple light sources) to emit light for a single image acquisition; using multiple EESD elements fired in series (e.g., coupled to multiple light sources, coupled to a single light source) to emit light for a series of multiple image acquisitions; using a first EESD element to power a first light source for a flash-type light emission and a second EESD element to power a second light source for constant/near constant light emission during a single image acquisition (e.g., having the flash-type light emission occur at the beginning of the exposure with the constant/near constant light emission at the later portion of the exposure (first curtain flash pop), having the flash-type light emission occur at the end of the exposure with the constant/near constant light emission at the earlier portion of the exposure (rear-curtain flash pop)); and any combinations thereof.

In one example, a lighting device includes a single light source coupled to the two or more EESD elements. In another example, a lighting device includes a plurality of light sources coupled to the two or more EESD elements. In one such example, each light source is coupled to a corresponding one of the two or more EESD elements. In another such example, two or more of the plurality of light sources are coupled to each of the two or more EESD elements. In yet another such example, two or more of the two or more EESD elements are coupled to each one of the plurality of light sources. In still another example, a combination of any of the previous examples is employed in a photographic lighting device. While several of the example implementations below will be discussed with respect to two or more EESD elements, it is contemplated that a single EESD element may be utilized with two or more light sources to provide one or more of the functionalities discussed below in each of the examples.

An EESD element includes storage circuitry for storing electrical energy necessary to power a light source of a photographic lighting device. A storage circuitry includes one or more storage devices. An example storage device is a capacitor. In one example, a storage circuitry and/or its one or more storage devices are capable of rapidly charging and discharging for allowing a light source to function as necessary to provide a desired light output. An EESD may also include and/or be associated with control circuitry for controlling the charging, discharging, and other operation of the EESD.

A light source for a photographic lighting device may be any light source capable of providing a desired light output for photographic image acquisition. Example light sources include, but are not limited to, a gas discharge tube (e.g., a halogen lamp, a xenon lamp), an LED (light emitting diode/device), an incandescent lamp, and any combinations thereof.

In one exemplary implementation, a photographic lighting device includes two or more light sources. A first light source is configured to fire a TTL preflash. A second light source is configured to fire a TTL main flash. In one example, each of the first light source and the second light source are connected to and powered by a separate corresponding one or more EESD elements. In another example, each of the first light source and the second light source are connected to and powered by the same one or more EESD elements. The first light source and the second light source can be of the same type or of different types. In one example, the second light source is a light source having a higher power output capacity than the first light source. In one such example, each light source is connected to its own EESD element/bank with the first light source providing a lower power output TTL preflash and the second light source providing a higher power output TTL main flash.

Some single light source lighting devices have a light source that has a minimum amount of power that can be applied thereto to cause light emission such that a light emission from such a light source may overpower (e.g., saturate) a sensor (e.g., a TTL metering sensor) of a camera if the light source is used for TTL preflash. Overpowering a sensor (e.g., a TTL metering sensor) may prevent a camera from providing proper main flash power information such that improper exposure may occur. In one exemplary aspect, an example lighting device with two light sources can include a light source that is capable of emitting light at a low enough power to provide a TTL preflash and a light source that is capable of emitting light at high enough power to provide a TTL main flash. In such an example, a higher power light source may also be capable of typical non-TTL (or TTL) high power studio strobe flash output levels, while having a second light source capable of providing a TTL preflash.

In one example, where two light sources are utilized for TTL preflash and main flash emission, the first light source for TTL preflash is in substantially similar optical path alignment with the second light source for TTL mainflash such that they both cast light in substantially similar beam angles upon a subject. One such example would be concentric ring tube light sources one within the other. In another example, the two light sources are selected with color temperature characteristics that are substantially similar such that metering of preflash is based on the same color temperature range as the main flash exposure. In one such example, this may provide a balanced exposure accuracy when a preflash and main flash have substantially the same color spectrum.

A photographic lighting device may include a crossover circuitry that will allow a second light source configured for TTL main flash output to be utilized for a TTL preflash at a higher power. For example, some camera bodies are configured for a low power TTL preflash and a high power TTL preflash. In one such example, a Nikon camera may provide a first low power TTL preflash command to a flash device and if insufficient light is detected through the lens for the first preflash, a second high power TTL preflash command can be provided to a flash device for providing a higher power preflash for TTL (e.g., to improve signal to noise). A crossover circuitry can be configured with hardware and/or executable instructions for a processing element/control circuitry for detecting a higher power TTL command from a camera and switching to using a higher power light source of the photographic lighting device for TTL preflash.

In some examples, a lower power TTL preflash may be needed when a subject is very close to a light source and/or when a low aperture lens (e.g., F1.4, F1.8, F2.8) is utilized at its larger open apertures.

In another exemplary implementation, a photographic lighting device includes two or more EESD elements coupled to one or more light sources for providing multiple symmetric light emissions within a single image acquisition. In one example, two or more EESD elements are coupled to a single light source. In another example, each of two or more EESD elements are coupled to a corresponding light source. Other combinations of EESD elements and light sources (e.g., other various combinations of multiple to single, multiple to multiple, single to single, etc.) are contemplated. In one example of multiple symmetric light emissions, a first light emission is powered by one or more EESD elements of the photographic lighting device and a second light emission is powered by one or more EESD elements of the photographic lighting device. The two light emissions are positioned in an image acquisition window such that they are spaced apart by a time period approximately the same as the shutter speed/exposure time for the image acquisition. In one example, spacing apart light emissions occurs by using an energy balance point (such as a half energy point for a light emission curve) for a light emission profile for the light source and spacing the energy balance point for each light emission within an image acquisition window such that the energy balance point of the first light emission is spaced a time period approximately the same (e.g., the same) as the exposure time/shutter speed value for the image acquisition from the energy balance point of the second light emission. The two light emissions can be approximately centered (e.g., centered) within the image acquisition window. In another example, the two light emissions can be positioned other than centrally in the image acquisition window.

In one example, a higher efficiency of light power output may be obtained by using two or more light emissions in a single image acquisition. In one such example, an improvement of 0.4 to 0.8 stops of light power efficiency over a typical HSS (high speed sync) or FP-sync (focal plane sync) in which a flash emission is kept near constant from before first shutter blade movement until after second shutter blade movement.

Three or more flash emissions may be utilized in other examples. In one such example, the spacing between light emissions is a time period equivalent to (exposure time/N−1), where N is the number of light emissions.

Additional examples are now discussed with respect to FIGS. 1 to 10. These examples and their aspects may be applied in any combination with the implementations discussed above. Referring now to FIG. 1, this figure illustrates a photographic strobe system 100 having a strobe light 104 and multiple electrical energy storage/discharge (EESD) banks, in this example two EESD banks 108, 112, that are independently operable relative to one another. As will be described below in detail, this independent operability of the multiple EESD banks gives a photographer great flexibility in controlling the amount and type of light provided by the photographic strobe system. Examples of type of light output that system 100 can be configured to output include: a through-the-lens (TTL) exposure flash (or “pre-flash”); a single image-capture exposure flash powered by one or more of the multiple EESD banks; an image-capture exposure burst powered by interleaving the discharges from the multiple EESD banks; an image-capture exposure continuous output; and any combination of these. Specific examples of these will be described below following a more detailed description of system 100.

Strobe light 104 includes one or more light sources 116 capable of providing both high-intensity flash light characteristic of flash photography and lower intensity constant or near-constant level light output. By “near-constant” it is meant that light source(s) 116 may be pulsed in a manner that simulates constant level light but nonetheless has inconsequential variations in level as an artifact of the pulsed operation. Examples of light sources suitable for use in strobe light 104 include, but are not limited to, electronic gas discharge lamps (such as xenon discharge lamps) and light-emitting diodes, and any combination thereof, among others. When one or more xenon lamps (color temperature of about 5500K to 6000K) are used as light source(s) 116 with, for example, a conventional current-generator digital single-lens-reflex (DSLR) camera, a TTL pre-flash can be a relatively low-intensity flash on the order of 8 microseconds to 1 ms, a single image-capture expose flash is a relatively high-intensity flash (for example, on the order of 1 ms), an image-capture exposure burst is a rapid series of single image-capture exposure flashes over, for example, one second or more, and an image-capture exposure constant-level output is a relatively low-to-moderate-intensity flash over a period of, for example, between 1 ms and 5 ms in a manner the same as or similar to focal-plane (FP) sync. FIGS. 2A-E illustrate exemplary intensity-versus-time curves and corresponding exemplary exposure periods for the flash modes just mentioned.

Referring first to FIG. 2A, this figure is a graph 200 illustrates intensity-versus-time curves for a TTL pre-flash (curve 204), a full-power, first-curtain image-capture flash (curve 208) and a reduced-power, first curtain image-capture flash (curve 212). Also shown is a characteristic exposure period 216 for capturing a single image to provide a reference for the occurrences of the various flashes relative to the exposure period. As readily seen, the TTL pre-flash (curve 204) occurs prior to the start of exposure period 216 and the full- and reduced-power first-curtain flashes (curves 208, 212, respectively) occur very shortly after the start of exposure period. FIG. 2B is a graph 220 illustrating intensity-versus-time curves for two second-curtain image-capture flashes, a full-power flash (curve 224) and a reduced-power flash (curve 228), relative to an exemplary exposure period 232. FIG. 2C is a graph 230 illustrating an intensity-versus-time curve 234 constant-level image-capture flash over a corresponding exposure period 238. As those skilled in the art will understand, curve includes a series of small peaks 242 caused by very rapid pulsing of the xenon light source. Curve 234 is very similar to a like-curve for the familiar focal-plane (FP) sync flash. FIG. 2D is a graph 250 containing a plurality of intensity-versus-time curves 254A-F representing a series of like-power image-capture flashes that all occur within a single, relatively long exposure period 258. As those skilled in the art will understand, graph 250 is characteristic of the classic strobe situation in which motion of a subject appears to be stopped in the acquired image at each time corresponding to the respective curve 254A-F within exposure period 258. FIG. 2E contains a graph 260 containing curves 264A-F that also represent like-power image-capture flashes. But instead of these flashes all occurring within a single exposure period as in graph 250, each of the flashes represented in FIG. 260 of FIG. 2E corresponds to a separate exposure 268A-F. Thus, graph 260 represents the rapid acquisition of a series of images using flash-lighting.

Referring again to FIG. 1, each EESD bank 108, 112 includes, respectively, storage circuitry 120, 124 for storing the electrical energy necessary to power strobe light 104. Each storage circuitry 120, 124 includes one or more storage devices (not shown), such as one or more capacitors, capable of the rapid charging and discharging necessary for system to provide the desired functionality. Such storage devices are known in the art, such that further explanation is not necessary. Each EESD bank 108, 112 also includes corresponding discharge circuitry 128, 132 for controlling the discharge of electrical energy from the corresponding storage circuitry 120, 124 to light source(s) 116, thereby controlling the intensity and duration of the light output from strobe light 104. As those skilled in the art will readily appreciate, discharge circuitries 128, 132 includes electronic components necessary to give system 100 the proper functionality. For example, if one or more xenon discharge lamps are used for light source(s) 116, such other components (not shown) might include, for example, one or more discharge quenching components, such as a quench tube, an insulated-gate bipolar transistor or other device that assists with the operation of system 100 during partial discharges, such as pre-flash discharges, reduced-power image-capture exposure flashes, etc. Those skilled in the art will readily understand how to design discharge circuitries 128, 132 appropriate for the type of light source(s) 116 used, such that further description of these circuitries is not necessary for those skilled in the art to make and use photographic strobe system 100.

EESD banks 108, 112 also includes corresponding respective charging circuitries 136, 140 configured for charging the respective storage circuitry 120, 124 from a suitable power source, here a pair of high-voltage power supplies 144, 148 that receive their power from a mains power source 158. Examples of mains power source 158 include, but are not limited to, an external battery, an internal battery, an A/C power supply (e.g. a connection via a power plug to an A/C power supply), a D/C power supply (e.g. a connection via a power plug to a D/C power supply). In other embodiments, the power for charging circuitries 136, 140 can be from a single power supply, and/or the power for the one or more power supplies can be from a source other than a mains power source, such as a battery. Those skilled in the art will readily understand how to design charging circuitries 136, 140 and high-voltage power supplies 144, 148 appropriate for the type storage circuitries 120, 124 used, such that further description of those circuitries and power supplies is not necessary for those skilled in the art to make and use photographic strobe system 100.

In this example, each EESD bank 108, 112 includes a bank controller 152, 156 that controls the charging and discharging functionalities of the corresponding bank. For example, relative to discharge control each bank controller 152, 156 controls parameters such as rate of discharge, magnitude of discharge and length of discharge so as to produce the desired light output from strobe light 104 for that bank. For example, when light source(s) 116 include(s) one or more xenon electronic discharge tubes, each bank controller 152, 156 may include quench circuitry (not shown) for determining when to quench the discharge from the light sources, for example, when system 100 is providing a TTL pre-flash, a reduced-power image-capture flash (e.g., reduced by manual control or based on a TTL exposure calculation), etc. As those skilled in the art will understand, such quench circuitry can include a light integrator (e.g., phototransistor+a capacitor) and a comparator for determining when strobe light 104 has output the desired amount of light. When the quench circuitry has determined that strobe light 104 has output the desired amount of light, it may send a signal to the quench circuitry of the corresponding discharge circuitry 128, 132. Each bank controller 152, 156 may also include constant-discharge circuitry (not shown) for controlling the corresponding discharge circuitry 128, 132 in a manner that strobe light 104 provides the constant-level light output described above. In some embodiments, such constant-discharge circuitry can take a form similar to conventional FP-sync circuitry.

Photographic strobe system 100 also includes a system controller 160 and a communications system 164 for communicating with a user interface (not shown) that allows a user to view and/or set operating parameters that control the operation of the strobe system and/or display information to a user such as current settings and/or status(es) of one or more components of the system. In this example, communications system 164 also receives a fire signal, which is typically initially triggered by a camera in response to a photographer actuating a shutter-release control. Depending on the design of photographic strobe system 100, communications system 164 can be a wired system, a wireless system or a combined wired and wireless system that handles all communications from and to system 100. Examples of types of wireless communication that communications system 164 can use include radio-frequency, infrared light, visible light, etc.

In this example, system controller 160 controls the overall operation of photographic strobe system 100 and can be effectively executed as a software-controlled machine, such as microprocessor, application-specific integrated circuit, system on chip, etc., that operates under the control of suitable software 168, such as firmware, as those skilled in the art will readily appreciate. One function of system controller 160 is to implement user-provided settings for causing photographic strobe system 100 to operate according to those settings. Another function of system controller 160 is to trigger each of EESD banks 108, 112 in response to receiving a trigger signal that is ultimately initiated by a photographer, for example, via a shutter-release button on a camera. Depending on the configuration of system, another function of system controller 160 is to provide various information to a user, such as current settings and one or more statuses, such as ready conditions of EESD banks 108, 112. Other functions that may be performed by system controller 160, depending on the overall functionality of system 100, include providing control data to bank controllers 152, 156 for causing EESD banks 108, 112 to drive strobe light 104 in the desired manner, deciding which EESD bank(s) to use and/or in which order to achieve the desired light output from the strobe light and calculating parameters necessary for causing EESD banks to drive light source(s) 116 in the appropriate manner. FIG. 3A-F illustrate exemplary intensity-versus-time curves and corresponding exemplary exposure periods for flash modes that photographic strobe system 100 of FIG. 1 can be configured and/or programmed to provide.

Referring now to FIGS. 3A-F, and also to FIGS. 1 and 2A-E occasionally as noted, FIG. 3A is an intensity-versus-time graph 300 illustrating an enhanced-intensity image-capture mode in which both EESD banks 108, 112 (FIG. 1) fire to provide more light than either one of the banks could provide alone. Assuming both EESD banks 108, 112 are identical (which they need not be), curve 304 illustrates the maximum intensity of light output by strobe light 104 powered by either of the EESD banks fired alone. Curve 308, however, illustrates the maximum intensity of light output by strobe lights 104 when EESD banks 108, 112 are fired simultaneously at maximum power. Here, the maximum intensity of curve 308 is essentially twice the maximum intensity of curve 304. In the context of strobe light 104 being a xenon gas discharge type light, curve 308 can be realized, for example, by providing two xenon-discharge-lamp light sources (not shown), each dedicated to a corresponding respective one of EESD banks 108, 112. Of course, either, or both, of EESD banks 108, 112 could be controlled to fire at less than full power, with the resulting light output being some value less than the power when both banks are fired simultaneously at full power.

FIG. 3B is a graph 310 illustrating a first curtain plus second curtain image-capture mode in which system controller 160 (FIG. 1) fires one of EESD banks 108, 112 to provide a first-curtain image-capture flash (curve 314) and fires the other EESD bank to provide a second-curtain image-capture flash (curve 318). Plot 319 illustrates a first shutter (first curtain) movement and second shutter (second/rear curtain) movement such that flash 314 is positioned proximate the first shutter blade opening and the flash 318 is positioned proximate the second shutter blade closing movement. As those skilled in the art will readily appreciate, system controller 160 can be set so that the power at which one of EESD banks 108, 112 fires is independent from the power at which the other fires to give the photographer maximum control over the lighting conditions

FIG. 3C is a graph 320 illustrating a first-curtain plus constant-level image-capture mode wherein system controller 160 (FIG. 1) fires one of EESD banks 108, 112 to provide a first-curtain image-capture flash (curve 324) and fires the other EESD bank to provide a constant-level flash (curve 328). Plot 329 illustrates a first shutter (first curtain) movement and second shutter (second/rear curtain) movement such that flash 324 is positioned proximate the first shutter blade opening movement and the constant-level light emission 328 is positioned proximate the second shutter blade closing movement. Those skilled in the art will readily appreciate that system controller 160 can be set so that the power of EESD banks 108, 112 are separately controllable.

FIG. 3D is a graph 330 illustrating a second-curtain plus constant-level image-capture mode wherein system controller 160 (FIG. 1) fires one of EESD banks 108, 112 to provide a second-curtain image-capture flash (curve 334) and fires the other EESD bank to provide a constant-level flash (curve 338). Plot 339 illustrates a first shutter (first curtain) movement and second shutter (second/rear curtain) movement such that flash 334 is positioned proximate the second shutter blade opening movement and the constant-level light emission 338 is positioned proximate the first shutter blade closing movement. Those skilled in the art will readily appreciate that system controller 160 can be set so that the power of EESD banks 108, 112 are separately controllable.

FIG. 3E is a graph 340 that shows a single exposure period 344 (corresponding to the acquisition of a single image) during which multiple like-power flashes are fired at a certain frequency, F, which will be at a maximum when the flash is fired immediately following recharging. In FIG. 3E, the flashes are created by system controller 160 (FIG. 1) alternatingly firing EESD banks 108, 112 so that each EESD bank fires at a frequency of F/2. This is represented in FIG. 3F by appending the curve identifiers with a “1” for EESD bank 108 and “2” for EESD bank 112. Consequently, flash-intensity-versus-time curves 348A1, 348B1, 348C1 are generated by firing EESD bank 108 and flash-intensity-versus-time curves 352A2, 352B2, 352C2 are generated by firing EESD bank 112. As those skilled in the art will appreciate, this alternating firing pattern allows for strobing strobe light 104 at a maximum frequency higher than the maximum frequency can be achieved with either of EESD banks 108, 112 standing alone. In the present case wherein there are two EESD banks 108, 112, the enhanced firing rate can be up to twice the firing rate of individual EESD banks. If more EESD banks are providing, the firing rate can be increased accordingly.

FIG. 3F is a graph 360 illustrating a rapid-fire, or burst, mode possible with a photographic strobe system made in accordance with the present disclosure, such as system 100 of FIG. 1. Graph 360 contains a series of flash-intensity-versus-time curves 364A1, 364B1, 364C1, 368A2, 368B2, 368C2 for like-power flashes fired at a constant frequency, much in the same manner as the flashes corresponding to flash-intensity-versus-time curves 348A1, 348B1, 348C1, 352A2, 352B2, 352C2 of FIG. 3E. That is, curves 364A1, 364B1, 364C1 result from system controller 160 (FIG. 1) firing EESD bank 108, and curves 368A2, 368B2, 368C2 result from firing EESD bank 112. However, unlike FIG. 3E, the flashes corresponding to flash-intensity-versus-time curves 364A1, 364B1, 364C1, 368A2, 368B2, 368C2 of FIG. 3F do not all occur within a single exposure period, but rather corresponding to respective exposure periods 372A-F for capturing a corresponding series of images (not shown). Like the flashes corresponding to curves 348A1, 348B1, 348C1, 352A2, 352B2, 352C2 of FIG. 3E, because of the interleaving the flashes corresponding to curves 364A1, 364B1, 364C1, 368A2, 368B2, 368C2 of FIG. 3F can occur at a frequency higher than the maximum frequency possible with either of EESD banks 108, 112 used alone. As those skilled in the art will appreciate, while flash-intensity-versus-time curves 348A1, 348B1, 348C1, 352A2, 352B2, 352C2 of FIG. 3F and curves 364A1, 364B1, 364C1, 368A2, 368B2, 368C2 of FIG. 3F are shown as being of the same maximum intensity, in alternative embodiments the maximum intensities may vary in any manner desired, as long as system controller 160 and/or other components of photographic strobe system 100 are suitably configured.

It is noted that the foregoing modes just described are merely exemplary of operating modes that can be achieved with a multi-bank photographic strobe system of the present disclosure. The type of mode, the number of individual flashes that occur within a particular mode and other characteristics of a particular mode can vary, not only as a function of the configuration of each EESD bank, but also with the number of EESD banks provided. Those skilled in the art will surely be able to devise useful modes other than those shown. It is also noted that, if desired, the system controller of such a multi-bank photographic strobe system can be configured so that the system is able to operate in any one or more “single” flash modes, such as the modes illustrated in FIGS. 2A-E described above.

FIG. 5 illustrates a strobe light 500 that can be used with, for example, a two-bank photographic strobe system, such as system 100 of FIG. 1. If used with system 100 of FIG. 1, strobe light 500 of FIG. 5 would be strobe light 104 of FIG. 1. Referring to FIG. 5, strobe light 500 is a gas-discharge-tube-type strobe light having a pair of gas-discharge tubes, in this example, like-sized xenon-discharge tubes 504A-B. In the parlance of FIG. 1, above, discharge tubes 504A-B would provide strobe light 104 with two light sources 116. Strobe light 500 is configured so that discharge tube 504A is electrically connected to, and driven by, only one EESD bank, such as EESD bank 108 of FIG. 1, and so that discharge tube 504B is electrically connected to, and driven by, only another EESD bank, such as EESD bank 112 of FIG. 1. The electrical connections between each xenon discharge tube 504A-B include connections that electrically connect a positive terminal 508A-B, a negative terminal 512A-B and a trigger 516A-B on each tube to corresponding circuitry (not shown) within the respective bank to which that tube is electrically connected. As those skilled in the art will readily understand, such circuitry can include one or more high-voltage storage devices, a trigger transformer, quench circuitry and one or more switches. Those skilled in the art will also appreciate that alternative embodiments can have, for example, two or more gas-discharge tubes connected generally in parallel to the corresponding EESD banks, if desired.

FIGS. 7 and 8 illustrate photographic strobe device 700 that incorporates at least some of a photographic strobe system of the present disclosure, such as system 100 of FIG. 1. Strobe device 700 includes a strobe light 704 and a body 708 that houses onboard circuitry and electronics (not shown) that enable system 100 of FIG. 1. Body 708 also houses an electrical energy storage battery 800 (FIG. 8) for powering the onboard circuitry and electronics. A user interface 804 (FIG. 8) is provided on the exterior of body 708 for allowing a user to program and/or otherwise control device 700 as desired. In this example, user interface 804 includes an electronic display 808 (LCD, OLED, etc.) and a keypad 812. Display 808 display information such as menus, settings, statuses, etc., and keypad 812 allows a user to enter settings, request information, change menus, make selections, etc. In this embodiment, strobe light includes a pair of light sources 712 (only one is visible, in FIG. 7), a reflector 716 and lens 720. Of course, many other photographic strobe devices may be made to include features of the present disclosure, such that those skilled in the art will readily understand that device 700 of FIGS. 7 and 8 is merely exemplary. Skilled artisans will readily understand how to make and use many variations of devices using only the present disclosure as a guide.

FIGS. 9 and 10 illustrate several examples of how a photographic strobe system made in accordance with the present disclosure, such as system 100 of FIG. 1, can be implemented in various photographic systems. Referring first to FIG. 9, this figure illustrates a camera system 900 that includes a camera, such as a DSLR camera 904 and a photographic strobe device 908. Depending on the configuration of camera 904 and/or strobe device 908, camera system can also include an interface device, such as a laptop computer 912. Laptop computer 912 can be configured with appropriate hardware and software to provide a convenient user interface to system controller 160 (FIG. 1) and/or to camera 904, for example, for settings various settings and operating parameters of those devices. Camera 904 can be configured to communicate with each of strobe device 908 and laptop either wirelessly (e.g., using one or more IEEE 802.15 and 802.11 communications protocols) or wiredly in a manner known in the art.

Referring to FIG. 9, and also FIG. 1, there are a number of ways that a photographic strobe system made in accordance with the present disclosure, such as system 100 of FIG. 1, can be implemented in camera system 900 of FIG. 9. For example, strobe device 908 can contain all of the components shown in photographic strobe system 100 of FIG. 1, such that communications system 164 receives directly from camera 904 information for triggering the firing of strobe light 116 in the proper mode. Depending on the configuration of system controller 160 (FIG. 1), the information provided by camera 904 can include a sync signal, camera exposure information, such as shutter speed, and/or information necessary for strobe device 908 to fire in the proper mode, such as power setting(s), mode setting(s), duration setting(s), etc. In some embodiments, some of the information needed to properly configure system controller 160 of effecting a desired firing of strobe device can be set prior to firing using camera and/or the user interface for strobe device 908 available on laptop computer, if any.

FIG. 10 illustrates a photographic system 1000 similar to photographic system 1000 of FIG. 10 except that system 1000 of FIG. 10 includes, in addition to camera 1004, strobe device 1008 and laptop computer 1012 (optional), an intermediate device 1016 that is configured to be an intermediary device between the camera and the strobe device. In this example, intermediate device 1016 acts to communicate, interpret and/or supplement information from camera 1004 for use by system controller 160 (FIG. 1) aboard strobe device 1008. Intermediate device 1016 may also include a user interface (not shown) for programming strobe device 1008 with the appropriate settings for providing desired operation during use. In one example, intermediate device 1016 is a photographic radio for controlling one or more aspects of communication between camera 1004 and strobe device 1008. In one such example, intermediate device is connected via a hotshoe connector of camera 1004. In another such example, intermediate device is internal to camera 1004. Intermediate device 1016 may include portions that are part of camera 1004, associated with camera 1004, connected to camera 1004, part of strobe device 1008, associated with strobe device 1008, connected to strobe device 1008, and/or any combinations thereof.

Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the spirit and scope of the present invention. 

What is claimed:
 1. A photographic lighting device including: a first light source; a second light source capable of emitting light at a lower output power than the first light source; a first EESD bank coupled to the first light source; a second EESD bank coupled to the second light source; and a control circuitry for causing a TTL preflash light emission using the second EESD bank and the second light source and for causing a TTL mainflash light emission using the first EESD bank and the first light source. 